Approximately 14 million in the USA suffer from diabetes mellitus. The present glucose sensing technique involves a finger puncture several times a day to obtain a droplet of blood for further analysis. There have been enormous efforts by many companies and scientific groups to quantify glucose concentration noninvasively. Optical coherence tomography (OCT), booming technology, is being applied for noninvasive imaging in tissues with high resolution. It utilizes sensitive detection of photons coherently scattered from tissue. We propose a novel glucose OCT sensor based on precise measurement of light scattering from skin that decreases with the increase of glucose concentration. The results of our preliminary studies performed in normal polarization in animals (bolus injections and glucose clamping experiments) demonstrated: (1) sharp and linear decrease of tissue scattering measured with the OCT system with the increase of blood glucose concentration and (2) the changes in tissue scattering at the depth of 150 to 500 mum are not induced by physiologic response due to bolus glucose injections. Specific aims of the project are: (1) to study OCT-based glucose sensing in normal and orthogonal polarization; and (2) to evaluate the OCT-based technique in animal and clinical studies. Successful implementation of the project may result in the development of a portable noninvasive sensitive glucose sensor that will considerably improve the quality of life for diabetic patients.